Comparative Studies Of The Resistance To Cadmium Stress For Populus Canescens And Populus Alba×P.Glandulosa Cv.84K In Vitro

Salicaceae populous is a model plant about resistance research and it is the better woody plant for phytoremediation also. Poplars have the developed root systems, fast growth, enormous biomass and the leaves can be collected easily and burned down centralizedly to facilitate the refining of heavy metals absorbed from the soil. Populus canescens and Populus alba×P. glandulosa cv.84K are both the good tree species for afforestation and beautiful green tree species. In this paper, the shoots of in vitro of Populus canescens and poplar84K were used as materials to study the effects of different cadmium levels on the growth of plantlets and the activity of antioxidant enzymes, and to discuss the difference of resistance between the two poplars species. The results obstained were as follows.1. With the increasing of concentrations of Cd2+stress, the growth indexes of Populus canescens and poplar84K in vitro (plantlet height, leaf numbers, root length, rooting numbers, dry weight, rooting rate) were similar to the trend.2. The low concentration (50μmol·L-1) of Cd2+stress could promote plantlet growth of populus canescens and poplar84K. Under low concentration of Cd2+stress, the number of leaves increased and leaves were normal, and the rooting rates, the numbers and length of rooting, and the plantlets height increased. The dry weights of populus canescens and poplar84K increased to151.45%and130.91%of control respectively. The effects of promoting were very obvious.3. The high concentration (200μmol·L-1) of Cd2+stress could inhibit plantlet growth of populus canescens and poplar84K. Under the high concentration of Cd2+stress, the number of leaves reduced and leaves turned yellow, and the rooting rates, the numbers and length of rooting, and the plantlets height decreased. The dry weights of populus canescens and poplar84K reduced to46.84%and17.79%of control respectively. The effects of inhibiting were very obvious.4. With the increasing of concentrations of Cd2+stress, the activities of SOD and CAT of the Populus canescens and poplar84K in vitro increased at first and then decreased, and the activities of POD gradually increased.5. At the low concentration(50μmol·L-1) of Cd2+stress, the SOD and CAT activities of plantlet leaves of Populus canescens and poplar84K were the highest, and the POD activities increased slowly. And the SOD, CAT, POD activities of Populus canescens increased to164.69%、135.29%and103.37%of the control, and those of poplar84K increased to111.25%、109.84%and104.47%of the control respectively.6. At the high concentration(200μmol·L-1) of Cd2+stress, the SOD and CAT activities of plantlet leaves of Populus canescens and poplar84K were the lowest, and the POD activities were the highest. And the SOD, CAT, POD activities of Populus canescens increased to124.85%、49.26%and227.01%of the control, and SOD and CAT activites of poplar84K reduced to93.70%,59.95%and POD increased to223.68%of the control respectively.7. Both Populus canescens and poplar84K have a certain resistance to Cd pollution, but Populus canescens has a higher resistance capacity than Poplar84K.